On Tue, May 1, 2012 at 12:50 PM, Eric Snow email@example.com wrote:
In my mind sys.implementation makes more sense. For example, in the case of cache_tag (which is merely a potential future variable), its value is an implementation detail used by importlib. Having it in sys.implementation would emphasize this point.
Personally, I think cache_tag should be part of the initial proposal. Implementations may want to use different cache tags depending on additional information that importlib shouldn't need to care about, and I think it would also be reasonable to allow "cache_tag=None" to disable the implicit caching altogether.
The ultimate goal would be for us to be able to eliminate implementation checks from other parts of the standard library. importlib is a good place to start, since the idea is that, aside from the mechanism used to bootstrap it into place, along with optional acceleration of __import__, importlib itself should be implementation independent.